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Proceedings Paper

Mid-infrared crystalline supermirrors with ultralow optical absorption (Conference Presentation)
Author(s): Christoph Deutsch; Garrett D. Cole; David Follman; Paula Heu; Bryce J. Bjork; Chris Franz; Alexei L. Alexandrovski; Oliver H. Heckl; Jun Ye; Markus Aspelmeyer

Paper Abstract

Substrate-transferred crystalline coatings are a groundbreaking new concept for the fabrication of ultralow-loss mirrors. The single-crystal lattice structure of these substrate-transferred GaAs/AlGaAs Bragg mirrors exhibits the lowest mechanical losses and hence unmatched Brownian noise performance, which nowadays limits the stability of precision optical interferometers. Another outstanding feature of these coatings is the wide spectral coverage of the GaAs/AlGaAs material platform. Limited by interband absorption at short wavelengths and the reststrahlen band at long wavelengths, crystalline coatings can be employed as low-loss multilayers from approximately 900 nm up to 5 μm and beyond. Excellent optical performance has been demonstrated in the near-infrared with excess optical losses (scatter + absorption) as low as 3 parts per million (ppm), enabling cavity finesse values up to 360,000 at 1.55 μm. Our first attempts at applying crystalline coatings in the mid-infrared has resulted in mirrors with excess optical losses of 159 and 242 ppm at 3.3 and 3.7 μm, respectively. Remarkably, these results are already on par with current state-of-the-art amorphous mirror coatings. Absorption measurements based on photothermal common-path interferometry (PCI) reveal that the optical losses are largely dominated by optical scatter. Via, PCI, we have confirmed absorption losses below 10 ppm at 3.7 μm, showing the enormous potential of GaAs/AlGaAs Bragg mirrors at mid-infrared wavelengths. An optimized fabrication process, which is currently under development, can efficiently suppress optical scatter due to accumulated growth defects on the surface. Ultimately, we foresee excess losses significantly less than 50 ppm in the mid-infrared spectral region.

Paper Details

Date Published: 21 April 2017
PDF: 1 pages
Proc. SPIE 10090, Laser Resonators, Microresonators, and Beam Control XIX, 100900A (21 April 2017); doi: 10.1117/12.2252517
Show Author Affiliations
Christoph Deutsch, Crystalline Mirror Solutions GmbH (Austria)
Garrett D. Cole, Crystalline Mirror Solutions, LLC (United States)
Crystalline Mirror Solutions GmbH (Austria)
David Follman, Crystalline Mirror Solutions, LLC (United States)
Paula Heu, Crystalline Mirror Solutions, LLC (United States)
Bryce J. Bjork, JILA, Univ. of Colorado, Boulder (United States)
National Institute of Standards and Technology (United States)
Chris Franz, Stanford Photo-Thermal Solutions (United States)
Alexei L. Alexandrovski, Stanford Photo-Thermal Solutions (United States)
Oliver H. Heckl, JILA, Univ. of Colorado Boulder (United States)
National Institute of Standards and Technology (United States)
Jun Ye, JILA, Univ. of Colorado Boulder (United States)
National Institute of Standards and Technology (United States)
Markus Aspelmeyer, Vienna Ctr. for Quantum Science and Technology, Univ. Wien (Austria)

Published in SPIE Proceedings Vol. 10090:
Laser Resonators, Microresonators, and Beam Control XIX
Alexis V. Kudryashov; Alan H. Paxton; Vladimir S. Ilchenko, Editor(s)

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